国外高温高压固井新技术

HPHT cementing technology abroad

介绍了国外几种高温高压油气井固井用新型水泥浆体系。柔性水泥浆配方中含有柔性外加剂、膨胀剂和常规外加剂,对挠曲强度和抗压强度、泊松比和渗透率、线性膨胀和水泥环寿命等性能指标的评价可知,该体系的特点是有弹性、可压缩性低、没有收缩、渗透率极低,可以避免由于井眼压力增加或温度升高引起的水泥环损坏。高密度高性能水泥浆体系(HDHPS)同常规水泥浆相比,浆体流变性可调、密度高(达2.88g/cm^3);具有更大的现场容忍性,更具稳定性;抗污染能力更强;有更高的抗压强度;在更宽的温度范围内,凝固更快、更均匀;最终的抗压强度更高;凝固水泥体积收缩少;凝固水泥的渗透率和孔隙度小。8次HDHPS作业均取得了很好的效果。介绍了北海Graben中部地区极高温/高压井(6口井平均井深在6000 m以上,温度超过 200℃.破裂压力与孔隙压力的区间很小,井底压力超过110 MPa,井斜最大达35°)固井的成功经验。

Several new cement slurry systems for HPHT (high pressure high temperature) cementing abroad are introduced. One is flex-cement slurry system, which consists of flex-cement additive, swelling agent and conventional cement additives. Evaluations to the flexible strength and compression strength, Poisson's ratio and permeability, linear expansion and cement ring life reveal that this system has elasticity and little compressibility, no contractility and little permeability. Damage to the cement ring caused by the rise of pressure and temperature can be eliminated. Another one is the high density high performance system (HDHPS), as compared with the conventional system, it has adjustable rheological property and high density ( 2. 88 g/cm3 ); furthermore, it is more tolerable to field conditions and more stable, and has better contamination resistance and higher compression strength. In a wide range of temperature, it sets faster and well-distributed, with higher final compression and little contraction, lower permeability and porosity. Good results are obtained in the 8 HDHPS cementing. The successful cementing of 6 wells with extremely high pressure and temperature in central Graben, North Sea is described.